App MiKey not installed [Miui Multi 5.1.23]

[JohnLocke]

Hi all,
when I try to install the app Mikey, my mi2s give me the error "Application not installed".. I've already tried to install this version:
http://app.mi.com/detail/59090
And this:
http://d-h.st/8zTs
How can I fix it?
Thanks